This competitive renewal retains its specific focus on the role of histone deacetylase (HDAC) activity in cystic fibrosis (CF), building on our substantia progress in the last funding period (2010 to 2014). CF is an inherited loss-of-function disease caused principally by a Phe508 deletion in the cystic fibrosis transmembrane conductance regulator (CFTR), referred to as F508del. We are now beginning to appreciate the importance of many other mutations in providing insights into synthesis, folding, trafficking and stability/function pathways that will be addressed in this competitive renewal focused on the deacetylation ('eraser') biology of HDAC7 in correcting F508del. CFTR is a multi-membrane spanning, cAMP-regulated chloride channel. Misfolding of F508del, and likely many other mutants, reduce the synthesis, folding, trafficking and/or stability/function of CFTR resulting in the loss of cell surface conductance, premature lung failure and shortened lifespan. As such, CF is a disease of proteostasis biology as we have demonstrated under auspices of the previous funding period and in the past. Proteostasis is the cellular environment that maintains the proteome for normal cellular function. It is frequently adjusted using multiple signaling pathways to protect the cell from protein folding stress during transient insult and in response to inherite, chronic misfolding diseases. The thrust of this competitive renewal is to seek correction of CF through an understanding HDAC7 deacetylation function. During the last funding period we provided evidence that HDACs, particularly HDAC7, can exert control through multiple avenues- transcriptional, translational and/or co-/post-translational programs that are linked to different components of the proteome through acetylation/deacetylation pathways. These can operate together to achieve a level of stability and function of F508del that can be protective and corrective for CF. Herein, we propose to focus on the enabling working hypothesis that the stability and function of wild-type (WT) and F508del CFTR is strongly influenced by the HDAC7 network of deacetylation activities that operate through transcriptional, translational and/or co-/post-translational mechanisms to direct protein function, and that the HDAC7 specific network can be manipulated to provide a protective environment for CF in the clinic. To explore our working hypothesis, we propose two aims: Aim 1 focuses on understanding the role of new targets revealed by the HDAC7 interactome generated during the last funding period that are likely responsible for HDAC7 function in correction of CF; Aim 2 focuses on approaches to understand the role of HDAC7 in (re)balancing acetylation-deacetylation pathways involved in correcting CF variants. The combined Aims will provide systematic approach to address HDAC7 regulated pathways affecting F508del synthesis, folding, trafficking and stability/function at the cell surface. They will provide an in-depth link to the cyclical acetylation- deacetylation environments regulated by HDAC7 that may be corrective for CF disease in the clinic